PION PHOTOPRODUCTION and the ISOSPIN = 0,1 RULE
Dynamics of low energy pion photoproduction
A.Donnachie and G.Shaw, Ann. Phys. (NY) 37(1966)333 [97 citations]
This was the main paper in my Ph.D. thesis. It used fixed-t dispersion relations and recently determined pion nucleon phase shifts to show that for photon enegies below 500 MeV, the multipole amplitudes could be understood in terms of the following dominant processes: (a) the Born terms(ie the nucleon and pion exchange contributions); (b,c) contributions from the Delta(1232) baryon resonance; and (d) unitarity/rescattering corrections in non-resonant multipoles.
Isospin properties of the electromagnetic current